A herbal approach to digestive health

Words - Catherine Rudenko

Introduction

The use of herbs and plant extracts to manage digestive ailments in other species is well documented. Whilst equine specific research is somewhat limited, some research is available and shows promising results. The principle common to traditional herbal medicines, whichever system is adopted, is that the patient is considered as a whole. This includes taking into account age, current level of vitality, emotional state or personality, along with environmental challenges. 

The digestive system is considered of primary importance as digestive health influences other aspects of health within the body. That traditional view is one that is now upheld firmly in modern science, as we become increasingly aware of the influence of gut health on other body systems. Within the human food sector there now exists a multitude of supplements targeting gut function, changing the microbiome, and promoting various health benefits derived from such changes. 

Plants present an opportunity to do more to manage digestive health for horses in training but supply and safety are significant challenges. Not all herbs are approved for use in racing as they contain substances that are banned in racing, for example ephedrine commonly found in Indian snakeroot, or synephrine that is often found in bitter orange cultivars. Just because a herb is available online and marketed for equine does not mean it is safe to use in racing. There is also the consideration of supply chain, as the global herbal market does not operate with the racing industry in mind. Whilst many herbs are themselves safe for use in racing by their action or composition, the supply chain may expose them to contamination with herbs or other materials containing banned substances. It is therefore essential only to use herbs and blends from companies operating under codes of practice, such as BETA NOPS who are assessing and managing the risk of contamination with naturally occurring prohibited substances (NOPS). 

The information below discusses some of the plants most commonly used or better evidenced for their effects on aspects of digestive health. Research is other species unless specifically stating equine. The information below is designed to provide an introduction to herbs commonly used for digestive health, the majority of which are available through reputable brands. 

Herbs noted for antiulcer or antacid effects

Turmeric (Curcuma longa)

Traditionally used for symptoms including inflammation, gastritis and gastric ulcer. In a study looking at the effect of curcuma longa extract the effects noted were reduced gastric acid secretion and protection against gastric mucosal lesions (1). Effect noted as from blocking of H2 histamine receptors.

Chamomile (Matricaria recutita)

One of the most widely studied herbs. Well known for its antioxidant and inflammatory properties. It has also been studied for its effects on management of diarrhoea and gastric ulcers (2). Effect likely from antioxidant properties.

Milk Thistle (Silybum marianum)

Milk thistle has been reported as having protective effects against ulceration through its positive effects on mucosa.

Fenugreek Seeds (Trigonella foenum-graceum)

Traditionally used for a variety of digestive disorders. Fenugreek seeds have been studied and compared with omeprazole for their protective effects against ulcers. In one study the soluble gel extract from fenugreek seeds was found to be as effective as omeprazole for experimentally induced ulcers (3).

Licorice (Glycyrrhiza glabra)

Well known for its antiulcer properties in humans and documented as an effective antacid. Research has shown that licorice used in donkeys with glandular ulcers induced by phenylbutazone was effective at reducing ulcer severity. Licorice was also effective at preventing associated phenylbutazone induced hypoglycaemia (4).

There are other herbs also with reported ulcer benefits mostly from a healing perspective including corydalis, gotu kola and bacopa. 

Combinations

Herbs are most often prescribed in combination, as a cocktail of herbs will provide more than one mode of action, and will take into consideration other aspects of a state of disease. 

Herbal combinations for ulcers within equine research is limited but some studies exist for marketed products. An Italian company has shown efficacy of a combination of minerals and herbs, namely fenugreek, licorice aloe vera and fleawort extract at reducing ulcer severity score of thoroughbreds in training (5). 

Another commercial preparation trialled in humans based on bitter candytuft, melissa leaf matricaria flower, caraway fruit, peppermint leaf, angelica root, milk thistle, elan-dine herb and licorice root was proven effective at lowering gastric acidity and inhibiting serum gastrin levels (6).

Herbs noted for anti-inflammatory effects of digestive disorders

Although gastric ulcers are the most common concern for horses the remainder of the digestive tract is equally challenged by the training environment and needs for high energy feeds. Herbs are often used, and well documented, for the management of human digestive disorders. Whilst there is not always a direct equine equivalent the similarities in conditions makes a herbal approach an interesting consideration. 

Boswellia (Boswellia serrata)

A potent anti-inflammatory herb with evidence for use in management of inflammatory bowel disease (IBD) and Chron’s disease. In both cases, research proves Boswellia as effective as medication in some studies. 

Chamomile (Matricaria recuita)

A herb with multiple benefits, including carminative effects. Widely used for any inflammatory condition of the bowel and gastrointestinal spasms. 

Demulcent Herbs

This group of herbs is used to lubricate and protect digestive tract membranes. Some herbs in this group are also in the anti-ulcerogenic group, highlighting that herbs are often carry multiple benefits across categories. Their primary mode of action comes from mucilaginous substances, namely polysaccharide gels, that protect mucosal surfaces by adhering to them. They may also act as prebiotics and influence intestinal flora. 

Marshmallow (Althea officinalis)

Used in humans for the management of inflammation of gastric mucosa.

Slippery Elm (Ulmus fulva)

Used for inflammation and ulceration of the stomach and for cases of colitis. 

Licorice (Glycyrrhiza glabra)

Licorice has a similar effect, although slightly different mode of action, through increasing mucus production and promoting mucosal blood flow.

Fenugreek (Trigonella foenum-graceum)

Used in the management of gastritis. 

Antimicrobial Herbs

There are numerous herbs with antimicrobial effects. The mostly widely studied group for gastrointestinal infections are those containing the active component berberine. It has been found effective in treating diarrhoea caused by Escherichia coli, Shigella dysenteriae and Salmonella paratyphi B, amongst others. Berberine is found in plants such as goldenseal, Oregon grape root and coptis root. 

Chamomile and thyme are also in this category although not of the berberine group. Chamomile oil is reported as having antifungal activity and activity against gram positive bacteria. Thyme oil has antifungal activities against a wide range of organisms. 

Antiviral Herbs 

Whilst there are several herbs considered as having antiviral properties, such as Echinacea, there is little information specifically for efficacy against gastrointestinal viruses. The exception being for tormentil root, which has been investigated for its effects against rotavirus diarrhoea in children. Research has shown an extract of tormentil root was effective in shortening the duration of rotaviral diarrhoea. 

Considerations

There is a considerable amount of research and evidence around the efficacy of some herbs, along with increasing understanding of their modes of action. As is often the case, equine specific research is limited and research from other species must be relied on. 

Herbs that are well researched, are worth considering alongside a well-balanced approach to nutrition. The main challenge is not finding evidence of efficacy, but finding a source that is most appropriate to racing. Although herbs and extracts are readily available online it is important to purchase through companies that are aware of the risks of naturally occurring prohibited substances and are managing this risk with a focus on racing, and not to use any supplement containing known banned substances. 

References

1. Kim DC, Kim SH, Choi BH, Baek NI, Kim D, Kim MJ, Kim KT. Curcuma longa extract protects against gastric ulcers by blocking H2 histamine receptors. Biol Pharm Bull. 2005, Volume 28, Issue 12

2. Mohamed-Amine Jabri, Nadhem Aissani, Haifa Tounsi, Mohsen Sakly, Lamjed Marzouki, Hichem Sebai. Protective effect of chamomile (Matricaria recutita L.) decoction extract against alcohol-induced injury in rat gastric mucosa. Pathophysiology, 2017, Volume 24, Issue 1

3. R Suja Pandian, C.V Anuradha, P Viswanathan, Gastroprotective effect of fenugreek seeds (Trigonella foenum graecum) on experimental gastric ulcer in rats, Journal of Ethnopharmacology, 2002, Volume 81, Issue 3

4. Masoud Ahmadnejad, Ghader Jalilzadeh-Amin, Benjamin W Sykes. Prophylactic effects of Glycyrrhiza glabra root extract on phenylbutazone-induced Equine Glandular Gastric Disease (EGGD). Journal of Equine Veterinary Science, 2022, V olume118.

5. Stucchi,L. Enrica,Z. Alessia,S. Giovanni,S. Serena,C. Contura,B. Ferro,E. Ferrucci,F. Efficacy of the administration of a natural feed supplement in the management of equine gastric ulcer syndrome in 7 sport horses: a field trial. American Journal of Animal and Veterinary Sciences. 2017, Volume 12, Issue 3

6. M.T. Khayyal , M. Seif-El-Nasr , M.A. El-Ghazaly , S.N. Okpanyi , O. Kelber , D. Weiser. Mechanisms involved in the gastro-protective effect of STW5 (Iberogast) and its components against ulcers and rebound acidity. Phytomedicine. 2006, Volume 13, Issue 1

Studying the feed behaviour of horses in training - why we keep on losing the battle with ulcers?

Article by Catherine Rudenko

Is this the biggest challenge when it comes to managing digestive health for horses in training? 

Keeping a racehorse healthy inside and out can be a real challenge. The nature of training and the environment in which racehorses live presents a constant set of risks. Managing those risks and balancing them against what is needed to achieve success is a fine art. 

So where does risk come from when it comes to digestive function? Are those risks manageable within the racing environment? What can you realistically expect to achieve with changes to feed, feeding practice and the use of supplements?

One of the biggest risk factors for digestive health is the stabled environment and the pattern of feeding required to fit in around a typical working day for stable staff, coupled with the need to get out on the gallops. On top of this is then the individual’s feeding behaviour, something that can easily be overlooked when the ‘what is fed’ is the same for all horses on the yard. Individual behaviour is perhaps one of the hardest aspects to tackle, whilst replicating a natural feeding pattern is nearly impossible.

The most common digestive concern is gastric ulcers, and many feeds and supplements are now available and marketed for this condition. Yet ulcers still exist and continue to frustrate many trainers despite making dietary changes. Why is this? The answer lies in gaining a better understanding of what a ‘good’ feed pattern and diet looks like from the horses’ perspective versus what is effective for performance and realistic in a typical racing yard. 

What is a natural feeding pattern?

Free ranging horses typically show 10-15 distinct feeding bouts in a 24-hour period (1).

Time spent resting or engaged in other non-feeding activities will not normally exceed 3-4 hours per session (2). Meaning the stomach is rarely truly empty.

The majority of feeding behaviour happens during daylight hours, typically 60-70% of time available (3).

During nighttime hours the amount of time spent as feeding behaviours reduces to 40-50% of those hours (3).

The total amount of time spent grazing across multiple feeding bouts is connected to the season and daylight hours. During summer months intake is around 14 hours in total versus 12 hours in the winter (4).

The natural feeding pattern is driven by the design of the horses’ digestive anatomy and is key to good health and normal function. The further away from these patterns we move any horse the greater the risk of dysfunction. 

What is a typical feeding pattern for a horse in training? 

The time study below shows the time taken for a group of 5 horses in training to eat their bucket feed and forage allocations in a 24-hour period. All horses in this observational study were in full training and worked in the morning of the study at different time points depending on their lot. Horses were observed from 4:45am until 9:15pm.  

One of the key aspects of natural feeding behaviour is the amount of feeding periods or ‘mini-meals’ a horse consumes. For 4 out of the 5 horses from completion of their evening forage to the next meal of breakfast was a period of time in excess of 8 hours , approximately 33% of the 24-hour period. During these nighttime hours feeding behaviour normally occurs in free ranging horses and supports regulation of the digestive system. 

For wild horses the total time spent eating is 12-14 hours in a 24 hour period. They do not normally have periods exceeding 12 hours in every 24 without some form of intake. For 4 out of the 5 horses there were distinct periods where all feed and forage had been consumed. The amount of time without any feed or forage available for the horses ranged from as little as 3 hours and 40 minutes up to 15 hours 30 mins in a 24-hour period.

Natural feeding patterns rarely see more than a 3-4 hour gap between each ‘mini-meal’ and at these points where gaps exist, it is important to remember that food has been available for 24 hours without restriction leading up to these chosen breaks in forage intake. The break in intake is short and during this time the stomach is unlikely to be truly empty. For horses in training it is easy to have periods in excess of 3 hours without any intake of feed or forage. 

Although the period from finishing breakfast to morning forage being given was for some horses less than 3 hours, the stomach when receiving that breakfast was in a fasting state. Ordinarily in the natural environment the stomach is rarely truly empty as it can take anywhere from 2-6 hours for the stomach to empty depending on what and how much has been consumed (5). When giving a bucket feed to a horse in a fasting state the rate of transit of that feed through the stomach will be relatively short, and depending on which lot the horse is pulled out for, can result in the horse being worked on an empty or near empty stomach. 

Why does this matter? 

One of the common causes of squamous ulceration is ‘acid splashback’ which relates to strenuous exercise and the movement of acidic content from the lower glandular region of the stomach to the unprotected squamous area (6). When the stomach contains feed or forage it is more difficult for the acidic content to be forced upwards to the squamous area. This is why it is recommended to include chaff in the breakfast feed or provide a small amount of forage as these fibrous sources are slower to pass through the stomach and can help reduce the level of acidity seen in the proximal portion of the stomach. The key point here is reduction not elimination. The practice will not prevent ulceration occurring, but it will reduce exposure.

The table below shows the difference between horses that were fasted for only 2 hours before exercise and those fasted for 18 hours. 

One of the challenges in racing is the differing amount of time between the breakfast feed and being saddled up for work. On top of this some horses will naturally consume their allocated feed faster. Even within the small number of horses observed in the study in Figure 1 there was notable variation in the time taken to eat the same amount of bucket feed given. Some of this variation comes from giving all horses the same breakfast by weight, which represents a different meal size against their bodyweight. Variation also exists as racehorses are individuals and appetite is flexible and influenced by other factors such as level of fitness and stress.  

Figure 3 shows the amount of dry matter provided in the breakfast feed to each horse and considers it against the bodyweight of the individual horse. The breakfast given was 2.2kg of a cubed racing feed alongside 0.6kg of an alfalfa based chaff. 

Can feed intake be slowed down?

In terms of feed format, pelleted feeds are consumed faster than mueslis or ‘sweet feeds’ (7). The addition of chaff mixed with the feed can slow intake, but for it to be effective there must be a reasonable amount given compared to the amount of pelleted or textured feed. As a rough guide, providing an additional 30% of the hard feed weight as a chaff will make a notable difference to the rate of intake. 

Whilst the aim is to slow intake it is important to keep in mind that feeding hard feeds too close to strenuous exercise is not recommended. Ideally feed is withheld for 2 hours before exercise. Forages, eg hay, haylage and alfalfa chaff, do not need to be removed but intake should be restricted to a small amount, typically 1kg. Providing a small amount of forage in this format helps maintain saliva production, which assists with regulation of acidity, and provides some fill for the stomach. 

Does forage intake matter?

Risk factors for gastric ulceration and colic when it comes to forage are similar. Diets low in forage and high in concentrates increase risk, along with intermittent feeding patterns and/or periods of fasting. 

In addition to what is given and the pattern that fits practically at a yard, is the fact that horses, like many other species, do not have a fixed rate of intake when a meal of any sort is presented. The majority will have a higher consumption rate at the start of feeding than at the end. With the observed horses hourly weigh backs of forage were carried out for a period of 6 hours to determine rate of consumption. During this time no bucket feed was present.  Figure 4 shows the individual intakes.

In the case of horses in training this is another problem to consider when it comes to evening feeds. Whilst the amount of forage given may be reasonable and in line with expected appetite, the feeding behaviour of the horse means there is not a consistent or regular intake of forage observed until the following morning feed.  True feeding of ad-lib forage, above what a horse needs or could eat in a 24-hour period, is rarely given and often impractical. The reality is that most horses in training will have a prolonged period of zero feed or forage intake during nighttime hours, which is the opposite of natural feeding behaviour. 

This is a practical challenge which for many yards is not easily overcome. Ideally forage should be fed at more regular intervals, rather than twice daily, to more closely replicate the 10-15 feeding bouts observed in wild horses. 

What can be done to improve feed patterns?

Simply put, the longer a horse spends eating the better. 

An enthusiastic eater that is ‘keen at the pot’ might be taken as a sign of good health, but a speedy intake that leads to a feeding pattern with longer periods between any sort of meal isn’t necessarily a good thing. A horse that appears a little slow with their forage but still consumes a good amount over a daily basis is not a bad thing as the pattern of eating is closer to multiple mini meals. 

• Using a good amount of chaff in every feed will prolong feed intake and requires additional chewing which helps increase salivation. 

• In the case of morning feeds ideally a little hay or haylage could be given, particularly for later lots to ensure the presence of some fibre in the stomach when working. Such a presence will not completely stop acidity in the delicate squamous area of the stomach, but it will reduce it. 

• Providing the evening forage as late as is possible to reduce the amount of time between evening forage being consumed and breakfast given. 

• Taking note of ‘speedy eaters’ and considering if hay nets or hay feeders would be appropriate to prolong the time taken to consume their evening allocation. Hay nets in different locations in the stable, for example one at the front and one at the back, can also influence how quickly all the forage is consumed. 

• Consider the type of forage given. Hay can be easier to provide on more of a free choice basis as horses will consume less hay than haylage on a dry matter basis in a set period of time (1).

What is a realistic expectation for managing digestive health?

The need for high energy intakes to fuel performance means reliance on hard feeds and a limited amount of forage. The horse does not have an unlimited appetite and even when provided with additional forage will not necessarily consume enough or consume it in a regular fashion. Replicating a natural feed pattern for horses in training is close to impossible and inevitably results in digestive disorders, but making changes and trying to reduce that risk is worth doing. The differences made may be small, but winning margins can be just as small.

The purpose of feeding low starch diets to horses in training is to reduce the specific element of risk that comes from high starch feeding. In doing so that element of risk is managed and the diet is one step closer to a more natural fibre-based diet. But it is one area of risk alone and mitigating this risk does nothing to control the risk of ulcers or colic from intermittent feeding, the impact of withholding water,  the effect of travel and the physical effects on the stomach from strenuous exercise in the case of ulcers.

Using supplements that support healing of tissues, the function of mucus barriers or buffer acidity in the stomach are all part of trying to manage gastric ulcers, a disorder that is created through the training environment and the intensity of work required to achieve a race fit state. Such supplements are not designed to treat or prevent ulcers, they are not medicines and should not claim to do so, but they play an important part in trying to maintain a healthy digestive system.

Equally using supplements that support hindgut function through promoting the growth of beneficial bacteria, stabilising the pH of the hindgut or ‘mopping up’ pathogenic bacteria are all part of trying to maintain a healthy hindgut, which has many benefits, and reduces the risk of disorder within this section of the digestive anatomy. 

The most important thing when considering gastric ulcers and other digestive disorders is to be realistic about what you can achieve within your environment, and to be realistic about what difference feeds and supplements alone can make. Any steps that can be taken to reduce risk are worth implementing as the aim is to keep the digestive system as healthy as possible so that the food you provide is converted to the nutrients needed to maximise performance and maintain general good health.

References

1. Ellis,A.D.,2010. Biological basis of behaviour in relation to nutrition and feed intake in horses. In A.D. Ellis, A.C.Longland, M.Coenen & N.Miraglia, ed. The impact of nutrition on the health and welfare of horses. The Netherlands: Wageningen Academic Publishers, 53-74

2. Ralston,1984; Vulink,2001, cited in Ellis,A.D.,2010. Biological basis of behaviour in relation to nutrition and feed intake in horses. In A.D. Ellis, A.C.Longland, M.Coenen & N.Miraglia, ed. The impact of nutrition on the health and welfare of horses. The Netherlands: Wageningen Academic Publishers, 58.

3. Vulnik,2001; Boyd 1988; Berger et al.,1999; Edouard et al.,2009 cited in Ellis,A.D.,2010. Biological basis of behaviour in relation to nutrition and feed intake in horses. In A.D. Ellis, A.C.Longland, M.Coenen & N.Miraglia, ed. The impact of nutrition on the health and welfare of horses. The Netherlands: Wageningen Academic Publishers, 58.

4. Vulnik,2001 cited in ELLIS,A.D.,2010. Biological basis of behaviour in relation to nutrition and feed intake in horses. In A.D. Ellis, A.C.Longland, M.Coenen & N.Miraglia, ed. The impact of nutrition on the health and welfare of horses. The Netherlands: Wageningen Academic Publishers, 59.

5. Frape, D. (2010) Equine Nutrition and Feeding. 4th Edition. United Kingdom: Wiley-Blackwell

6. Lorenzo-Figueras,M. Merrit,AM. Effects of exercise on gastric volume and pH in the proximal portion of the stomach of horses. Am J Vet Res. 2002;63(11):1481-1487

7. Hintz et al 1985 cited in Geor,J. Harris,P. Coenen,M. (2013) Equine Applied and Clinincal Nutrition. China: Elsevier